In the geological exploration, mining and construction industries, among others, drill bits are used to drill through rock, concrete and other materials. Typically, these bits include a crown made of a mixture of metal and diamonds. This crown is the portion of the bit that erodes the material through which a bore is drilled.
Some bits include a central passageway through which water is injected. To let water and debris flow out of the drill's way, the crown typically includes a plurality of segments separated by openings.
The crown material used to manufacture the crowns of the bits is typically substantially harder than the material through which drilling is performed. However, this crown material is typically relatively brittle. Accordingly, the dimensions of the openings between the segments in the crown are limited by the brittleness of the material used to manufacture these crowns.
Indeed, if these openings extend too deep within the crown, there is a risk that a segment will be broken while drilling. In this case, there is a need to remove the bit from the drilling apparatus and to use a new bit.
Since these drill bits are relatively expensive, the size of the segments are typically limited in currently existing bits, as shallower openings between the segments render the latter typically less prone to being ruptured or otherwise damaged. This shallowness of openings is a desired characteristic as breaking a segment typically means that the whole bit must be discarded. In addition, the time required to remove the drill bit and to position the new bit inside the bore that was being bored is typically relatively long as the bit and drilling apparatus need to be removed entirely from this bore in order to replace the damaged bit.
However, bits including relatively shallow openings will be worn from drilling in a relatively short amount of time. Therefore, once more, there is a need to take time to remove the bit from the bore to drill at relatively short time intervals to replace the worn out drill bit.
U.S. Pat. No. 5,316,416 issued on May 31, 1994 to Kim describes a drill bit that attempts to alleviate this disadvantage of previously known drill bits. In this patent, a drill bit including a tool body having an open upper end and an annular diamond blade portion is described. The diamond blade portion includes an upper circumferential edge and a lower circumferential edge, the diamond blade portion being attached at the lower circumferential edge to the open upper end of the tool body. A plurality of upper cuts each extends downwardly from the upper circumferential edge of the diamond blade portion. The upper cuts terminate at a depth of the diamond blade portion above the lower circumferential edge. A plurality of lower slots each extends upwardly from the lower circumferential edge of the diamond blade portion and terminate at a height below the upper circumferential edge. The lower slots are positioned under and between the upper cuts and extend higher than the bottom of the upper cuts.
However, the configuration of this drill bit is not suitable for use in wet drilling wherein water is injected inside the drill bit during the drilling process. Indeed, the configuration of the cuts in this drill bit does not allow the water to flow radially outwardly towards the outside of the drill bit as no longitudinal passageways are present that would allow the water to move away from the crown of the drill bit after it exits the crown.
Another problem that sometimes occurs in prior art drill bit is that the drilling process may produce a radially uneven abrasion of the crown. In cases wherein this phenomenon occurs, the efficiency of the drilling process is reduced relatively to cases wherein the crown is abraded substantially uniformly.
Against this background, there exists a need in the industry to provide an improved drill bit.